358 BAUR. [Vol. IV. 



firm after the study of the evolution of the pelvis in the most 

 primitive Batrachian Necturus. 



From a form of pelvis as seen in Palaeohatteria it is only one 

 step to the Batrachian pelvis ; for instance, Necturus. Here 

 the gastroid cartilage is greatly developed, pierced only by the 

 small obturator foramen ; only the ischia are ossified ; the pubes 

 are not distinct from the gastroid cartilage. One step lower, 

 and we have the pelvis of the Dipnoa or Chlamydoselachus, only 

 represented by the gastroid cartilage. 



H 



Fig. 12. — PalcEohatteria, Credner. FiG. 13. — Necturus maculatus, Raf. 



E, Epigastroid. E, Epigastroid. 



M, Mesogastroid. M, Mesogastroid. 



H, Hypogastroid. H, Hypogastroid. 



/, Ischium. /, Ischium. 



Wiedersheim has expressed the opinion that the single median 

 gastroid cartilage (" unpaare ventrale Beckenplatte ") in the Dip- 

 noa takes its origin from two halves. The pelvis of Necturus 

 is nearest to the pelvis of the Dipnoa, and in this form the 

 gastroid cartilage develops from two halves. In a specimen 

 25 mm. long the gastroid cartilage is represented by two lateral 

 portions ; in a little older stage the two halves are united, re- 

 main united, and extend now forwards, forming the long epigas- 

 troid portion. 1 



There is one element in the pelvis which has to be mentioned 



1 I may mention here the fact that Necturus, like Proteus (Wiedersheim), develops 

 its limbs like all the other Urodela examined, by budding. There is never an indica- 

 tion of more than four digits. This seems to be another proof for my theory that the 

 limbs of the Stapedifera have developed by budding, and that the ancestors of the 

 Stapedifera were not, as it is generally believed, polydactyle forms. Baur, G. : Rei- 

 tr'dge zur Morphologie des Carpus und Tarsus, Jena, 1888. 



